The present invention relates to a hinge device which swingably joins and holds a door or the like in an opened state or a closed state, and an ultra-deep freezer which uses the same.
Hitherto, a door or a cover provided at an opening is held in an opened state or a closed state by a hinge device swingably supported on one side of the opening. For example, the hinge device disclosed in Japanese Patent Application Laid-Open No. 10-61306 (patent document) is constructed of a first hinge member screwed to a main body, a second hinge member screwed to a door, and a hinge pin (a pin assembly).
The first hinge member has a mounting base and two knuckles formed on the mounting base with a predetermined distance provided therebetween in a direction in which the hinge pin extends. The second hinge member includes a mounting base and a locking knuckle for locking which is formed on the mounting base and which is placed between the knuckles of the first hinge member. Each knuckle of the first and the second hinge members has a through hole in the direction in which the hinge pin extends. The hinge pin is inserted in the through holes set in alignment, thereby holding the door, to which the mounting base of the second hinge member has been secured, such that the door swings on the hinge pin relative to the main body, to which the mounting base of the first hinge member has been secured.
In the conventional hinge device, each of the mounting bases has a plurality of screw holes for screwing the mounting base to the main body or the door. Further, each of the mounting bases has a removable cover for concealing mounting screws to be inserted in the screw holes.
In general, the mounting base is made of zinc die-casting, whereas the cover is made of a metal material, such as stainless steel. Further, the outer surface of the mounting base and the side surfaces positioned adjacently to both ends in the axial direction of the hinge pin have stepped portions for installing the cover, and both side surfaces have grooves for projections, which are formed on the cover, to be retained by fitting therein.
Thus, the cover is fitted to the stepped portion of the mounting base while slightly bending the cover, and the projections formed on the inner surface of the cover are fitted in the grooves in each of the mounting bases, thereby making it possible to install the cover to the mounting base.
The aforesaid construction, however, has been posing a problem in that the cover cannot be easily removed unless a tool, such as a flathead screwdriver, is inserted between the side surface of the mounting base adjacent to both ends in the axial direction of the hinge pin and the cover when detaching the cover from the mounting base for the purpose of maintenance or the like.
Hence, there have been a problem of preventing easy removal of the cover and also a problem of the possibility of scratching the cover and the side surfaces of the mounting bases by tools, resulting in deteriorated appearance, damage or the like.
The present invention has been made to solve the problems with the prior art, and it is an object thereof to provide a hinge device which permits easier attachment and detachment of a cover installed to a mounting base, and an ultra-deep freezer which uses the same.